1. Field of the Invention
The present invention generally relates to the testing of sensor systems and, in particular, to a system of generating an infrared scene using a fluorescent conversion material (FCM).
2. Background Information
The use of infrared (IR) imaging sensors, both mid-wave infrared (MWIR) operating approximately in the 3-5 xcexcm waveband and long-wave infrared (LWIR) operating approximately in the 7-12 xcexcm waveband, have become common in both the commercial and military applications. In military and security systems, for example, IR imaging sensors have often been used to monitor and visually describe spatial areas to determine the presence or movement of objects within the area.
A sensor system accomplishes this by detecting the various temperatures in an area and then by generating an image showing the distribution of temperatures. Such an image or xe2x80x9cscenexe2x80x9d is used to determine, among other information, the shapes of objects in the area and their proximity to the sensor system. An example of a sensor system used for scene generation is described in U.S. Pat. No. 5,710,431, the disclosure of which is hereby incorporated by reference in its entirety. In a military setting, for example, objects detected may be enemy troops or vehicles; therefore, it is essential that the IR imaging sensors be precisely calibrated, sighted, and in otherwise perfect working order.
To accurately and completely characterize the performance of a system utilizing such sensors, it is advantageous to be able to generate synthetic infrared scenes in a controlled laboratory environment. The most widely used IR scene generator produces images with an array of resistive heaters, also known as a microbolometer. However, this type of device has numerous shortcomings.
First, a microbolometer takes time to both heat up and cool off, approximately 15 milliseconds for each transition. Second, with resistive heaters, long periods of time spent simulating a bright source will cause adjacent areas of the array to heat up, causing the scene in these areas to be wiped out. And third, the microbolometer must have a very large number of small resistors to achieve high resolution. Any failure of one of these heating elements will reduce the quality and capability of the scene generator.
What is needed is a system for testing IR imaging sensors by generating laboratory-controlled IR scenes in a way that is fast, accurate, and relatively inexpensive to manufacture.
The present invention is directed to a system using a fluorescent conversion material for generating detailed, dynamic IR scenes that can be used in testing IR imaging sensors.
According to a first embodiment of the present invention, an infrared scene generator is provided, comprising a plurality of sources emitting energy at a first set of wavelengths, a fluorescent conversion material, a plurality of beam steering optics directing the emitted energy onto the fluorescent conversion material, wherein the first set of wavelengths are absorbed and radiated by the fluorescent conversion material as a second set of wavelengths, and an infrared imaging sensor detecting energy of the second set of wavelengths.
According to a second embodiment of the present invention, a system is provided for generating an infrared scene, comprising first emitting means for emitting energy of a first wavelength, converting means for converting the energy of a first wavelength to energy of a second wavelength using fluorescent conversion, and sensing means for detecting energy of the second wavelength.
According to a third embodiment of the present invention, a method is provided for generating an infrared scene, comprising the steps of emitting energy of a first wavelength, converting the energy of a first wavelength into energy of a second wavelength using a fluorescent conversion material, and detecting energy of the second wavelength.